Light is refracted when it crosses the interface from air to glass in which it moves more slowly.
Since the light speed changes at the interface, the wave length of the light must change too. The wave length decreases as the light enter the medium and the light wave changes direction.
The answer is Rarefaction
Since momentum is equal to mass multiplied by velocity, you would mulitply 250 grams by 68 m/s.
The answer is 17,000 kg*m/s
The box is kept in motion at constant velocity by a force of F=99 N. Constant velocity means there is no acceleration, so the resultant of the forces acting on the box is zero. Apart from the force F pushing the box, there is only another force acting on it in the horizontal direction: the frictional force

which acts in the opposite direction of the motion, so in the opposite direction of F.
Therefore, since the resultant of the two forces must be zero,

so

The frictional force can be rewritten as

where

,

. Re-arranging, we can solve this equation to find

, the coefficient of dynamic friction:
Answer:
Explanation:
Given that,
The temperature of atom is 21°C
θ = 21 + 273 = 294K.
Then, from kinetic theory,
The kinetic energy of individual elements is
K.E = 2kT/3
k is Boltzmann constant
k = 1.38 × 10^-23 J/K•particle
Then,
K.E = 2 × 1.38 × 10^-23 × 294 / 3
K.E = 2.7048 × 10^-21 J/particle
Each particle of hydrogen is 5.64 × 10²¹ particle
Total K.E = 2.7048 × 10^-21 × 5.64 × 10²¹
Total K.E = 15.26 J